Many of the bolded characters in the characterization above are apomorphies of more or less inclusive clades of streptophytes along the lineage leading to the embryophytes, not apomorphies of crown-group embryophytes per se.

All groups below are crown groups, nearly all are extant. Characters mentioned are those of the immediate common ancestor of the group, [] contains explanatory material, () features common in clade, exact status unclear.

For discussion as to where characters of pollen morphology and development are to be placed on the tree, see M. L. Taylor and Osborn (2006) and also Friis et al. (2009b); it partly depends on how the characters are defined and partly on the recent discovery of fossil Nymphaeales that do not have the pollen characteristics of extant members of the clade. For vessel evolution in angiosperms, including that in Nymphaeales, see the Amborellales page.

For cell lineages in the embryo sac see Huang and Russel (1992) and Friedman (2006); identification of the pattern described above apparently goes back to Porsch (1907), although it has been observed for relatively few plants. For embryo sac evolution, see Friedman and Ryerson (2009). For the possibility of a genome duplication at about this position, see Cui et al. (2006) and dePamphilis et al. (2009).

Phylogeny. For discussion of the relationships of Nymphaeales, see the Magnoliophyta node.

Note: In all node characterizations, boldface denotes a possible apomorphy, (....) denotes a feature the exact status of which in the clade is uncertain, [....] includes explanatory material; other text lists features found pretty much throughout the clade. Note that the particular node to which many characters, particularly the more cryptic ones, should be assigned
is unclear. This is partly because homoplasy is very common, in addition, basic information for all too many characters is very incomplete, frequently coming from taxa well embedded in the clade of interest and so making the position of any putative apomorphy uncertain. Then there are the not-so-trivial issues of how character states are delimited and ancestral states are reconstructed (see above).

The curious fossil Archaefructus, probably an aquatic plant and about 124 m.y. old, has been linked with Hydatellaceae in morphological analyses (Doyle & Endress 2007, 2010; Doyle 2008b). Although they have very little in common in terms of overall appearance, Archaefructus may be another early aquatic angiosperm with very unconventional floral morphology. Hydatellaceae may be represented in the pollen record from the Isle of Wight in rocks of some 130 m.y. of age (Hoffmann & Zetter 2010).

Numerous other fossils have been identified as members of Nymphaeales; these are discussed below under Cabombaceae and Nymphaeaceae.

Evolution:Divergence & Distribution. Cretaceous fossils assignable to Nymphaeaceae are quite common, and it has been suggested that Nymphaeales were "the first globally diverse clade" (Borsch " Soltis 2008: p. 1051; see also Sender et al. 2010). However, looking only at extant taxa, their diversity is slight.

Saarela et al. (2007) suggest a few additional possible synapomorphies for Nymphaeales, and Zeng et al. (2014) thought that having protoxylem lacunae and vascular bundles lacking associated sclerenchyma might be apomorphies. For the development of root hairs, see e.g. Clowes (2000) and Sokoloff et al. (2008a), Borsch et al. (2007) discuss the evolution of a number of floral characters within the order, M. L. Taylor et al. (2015) outline palynological variation in the context of the phylogeny of the order, and Endress and Doyle (2015: floral morphology) also suggest apomorphies. Understanding where some of these should be placed on the tree is complicated by the highly autapomorphic nature of Hydatella and some lingering uncertainty over the position of Nymphaeales.

The development of perisperm (2n, maternal, c.f. endosperm, 2n, maternal/pateral) is an apomorphy for the order. Povilus et al. (2018 - read the details carefully) examined seed development in Nymphaea thermarum and interpreted perisperm development there as a way for the female parent to control resource allocation to the offspring.

As might be expected, endomycorrhizae are at most uncommon here (e.g. de Marins et al. 2009).

Chemistry, Morphology, etc. Hydrolysable tannins in this group (e.g. in Nuphar) are different to those found
elsewhere (Gottlieb et al. 1993; Ishimatsu et al. 1989) - although of course Hydatellaceae are here, as in many other features, very poorly known. Although there are minute perforations in the end walls of the cells that make up the water conducting tissues in some Nymphaeaceae, they hardly have the morphology of what are called vessel elements elsewhere, however, there are vessels of a variety of types in the
roots in the stems of Brasenia. Hydatellaceae also have vessel elements with scalariform perforation plates, although these are absent from the leaves. The distinctive uniseriate trichomes found in all groups may secrete nectar or mucilage, or they may be involved in ion exchange (Vogel 1998a); Wilkinson (2006) calls the trichomes on the leaves, hydropotes. It is possible that there are epidermal oil cells in Nymphaeaceae (Wilkinson 2006); do they contain ethereal oils?

The inner bracts found in some Hydatellaceae and the inner petals of Cabomba are notably slow in developing (Rudall et al. 2007). If the corolla represents sterilised stamens, as some think, having external staminodes will probably be another synapomorphy at least for [Nymphaeaceae + Cabombaceae]. For discussion about the presence of a granular infratectum in Nymphaeales, see M. L. Taylor et al. (2013, 2015, also 2014 for other characters); the infractectum is generally columellate, how obviously so depending on the thickness of the infratectal space. Some genera in all families have exotestal cells that are neither very tall nor much thickened (Hamann et al. 1979; Collinson 1980). For the distinctive single-celled chalazal endosperm haustorium, see Rudall et al. (2009b); in general, the endosperm is slight and it probably functions as transfer tissue betweem embryo and perisperm (Friedman et al. 2012). Baskin and Baskin (2018) discuss embryo morphology and seed germination.

Phylogeny. Hydatellaceae are sister to Xyridaceae in Stevenson et al. (2000; see also Stevenson & Loconte 1995); both have latrorse anthers and seeds with an operculum "stopper" that is tegmic in origin. Trithuria and Xyris appear as sister taxa (weak support) and in turn are sister to Mayaca (still weaker support), although other Xyridaceae are not immediately related in the phylogeny of Michelangeli et al. (2003). However, although Bremer (2002) noted that Mayacaceae and Hydatellaceae might be weakly associated with Xyridaceae or Eriocaulaceae, depending on what taxa were included in the analysis, there were a number of long branches in this area and he excluded the first two families from his final analysis, while Janssen and Bremer (2004) suggested that the association of Hydatellaceae with Mayacaceae was probably an artefact (see also Chase et al. 2006). Subsequent studies (Saarela et al. 2006, esp. 2007: several genes from two compartments, morphology; Friis & Crane 2007: commentary) placed Hydatellaceae firmly with Nymphaeales, and sister to [Cabombaceae + Nymphaeaceae]; the sequence that placed Hydatellaceae in Poales was a chimaeric pcr recombinant involving a grass and a moss.

Hydatellaceae aside, for a morphological phylogeny of [Cabombaceae + Nymphaeaceae], see D. W. Taylor (2008). Y.-L. Liu et al. (2005) provide an ITS phylogeny focussing on Nymphaeaceae, but with some at first sight rather surprising relationships - [Nuphar [Cabomba + Brasenia] [Nymphaea [Euryale + Victoria]]]. Nelumbo, which was included in the analysis, did at least stay outside this clade... However, this position of Nuphar is recovered in other analyses, too (e.g. Borsch et al. 2008; Löne et al. 2007; D. W. Taylor & Gee 2014: some analyses; Gruenstaeudl et al. 2017) and so its position below sister to Nymphaea, etc., must be considered provisional.

Previous Relationships. Many of the morphological features of Hydatellaceae that made it so different from other monocots are consistent with a position in Nymphaeales. Hamann (1998) had even noted that the antipodal cells were absent or degenerated early, and absence of these cells would almost be expected if Hydatellaceae were to be placed here, indeed, Friedman (2008a) and Rudall et al. (2008) found that Hydatellaceae had the distinctive 4-celled embryo sac of other Nymphaeales and of Austrobaileyales.

Age. It has been estimated that crown-group Hydatellaceae are (23.4-)19.1, 17.6(-14.7) m.y.o. (Iles et al. 2014).

The pollen Monosulcites riparius in ca 75-70 m.y.o. rocks from Eastern Siberia has been identified as Trithuria, but this must be a misidentification if the ages above hold.

Hydatellaceae are rather small more or less caespitose and
often annual aquatic (submerged or not) herbs with linear leaves that have only a single vein, and capitate and usually scapose inflorescences bearing
minute and very reduced flowers; the beaded, penicillate stigmas are
distinctive.

Evolution:Divergence & Distribution. For the evolution and biogeography of the family - crown Hydatellaceae are certainly not Gondwanan in age - see Iles et al. (2014); Trithuria konkanensis (India) and T. lanterna (N. Australia) diverged (1.3-)0.76(-0.24) m.y.a. and evolution in the genus seems in general to be pretty active (e.g. Marques et al. 2016 and references).

Genes & Genomes. For chromosome numbers, see Marques et al. (2016). The genome of Trithuria submersa shows signs of polyploidy (n = 28), and the chromosomes of one of the genomes involved appear to be holocentric (Kynast et al. 2014).

Chemistry, Morphology, etc. The sieve tube plastids were reported as having triangular proteinaceous inclusions, but the inclusions appear to be of the starchy type as are more to be expected in this part of the tree (Tratt et al. 2009). There is some variation in the epidermis of the root and whether or not root hairs are produced (Sokoloff et al. 2008a). Hairs with possible apical secretory cells are known only from the inflorescences.

The inflorescence is described as being cymose and capitate, although bractless and with highly reduced flowers, i.e., it is a sort of pseudanthium, although alternative interpretations are possible (Rudall et al. 2007a, 2009a). The pedicels seem at least sometimes to be articulated. Early work suggested that the carpels might be initiated outside the stamens, and this has been confirmed (Rudall et al. 2007a); staminate flowers are the first to be initiated in the cymose inflorescence (see also Begoniaceae). However, how the reproductive structures are to be interpreted, whether flowers or inflorescences, is unclear, and Sauquet et al. (2017) elected not to include the family in their study of the morphology of the ancestral angiosperm flowers.

The fruit opens along three lines as the three vascular bundles separate from the rest of the pericarp (see also Sokoloff et al. 2013a). Both integuments have two cell layers; the operculum is formed from enlarged cells of the inner integument. Starch deposition in tissues that will become perisperm begins before fertilization (Friedman 2008a).

There is some disagreement over the interpretation of the morphology of the embryo. Tuckett et al. (2010: discussion of "ancestral" embryo type for angiosperms must include Amborellaceae, at least; see also Sokoloff et al. 2014) found that the embryo differentiated and the shoot and root appeared only after germination began. Tillich et al. (2007) compared seedling morphology with that of a monocot, describing collar rhizoids, a coleoptile, two cotyledonary sheath lobes, and a haustorium. Sokoloff et al. (2008a) suggested that the sheathing structure with its bilobed apex that is found in some species could be interpreted as two more or less completely connate cotyledons. The rest of the embryo is attached to the sheathing structure, and a layer of endosperm is the intermediary between it and the perisperm (Friedman et al. 2012). In some taxa there is apparently no sheathing structure at all, only a haustorial lateral outgrowth (cotyledonary) that goes into the rest of the seed, the rest of the cotyledon being photosynthetic, so the seedlings are simultaneously both phanero- and cryptocotylar - c.f. some monocots (Sokoloff et al. 2013b), and Sokoloff et al. (2008a, 2014) suggested that Hydatellaceae showed how monocot-like embryos/seedlings might have originated. Some species are phanerocotylat (Sokoloff et al. 2013b). Both Tillich et al. (2007) and Sokoloff et al. (2008a) examined largely the exterior morphology of the embryo, neither looked in any detail at anatomy (c.f. Friedman et al. 2012: superb micrographs; Sokoloff et al. 2014); for a discussion on germination, see Baskin and Baskin (2018).

Meiosis during microsporogenesis has a number of odd features, and it is possible that (some of) the chromosomes are holocentric (Kynast et el. 2014).

Previous Relationships. Hydatellaceae had long been considered to be monocots, largely because of their superficial similarity to Centrolepidaceae (= Restionaceae). Both groups are very reduced morphologically, and indeed Hydatellaceae have been misidentified as Centrolepidaceae. It was unclear if the gynoecium of Hydatellaceae was 1- or 3-carpellate, and since the fruits of Trithuria (= Hydatella) opened by three valves, they looked rather monocot-like. The combination of characters in Hydatellaceae was recognised as being unique to that group, and it made them very distinctive within monocots as a whole (e.g. Hamann et al. 1979; Dahlgren et al. 1985).

Age. There has been much discussion over the timing of diversification within the Cabombaceae-Nymphaeaceae clade (e.g. Nixon 2008), however, the disagreement is not a simple morphology vs molecules dichotomy. Wikström et al. (2001) suggested that divergence of the two families occurred (152-)144, 111(-103) m.y.a. and the figure in Salomo et al. (2017) is (117-)110(-106) m.y.a., while the age in Magallón and Castillo (2009) is ca 112 m.y. (see also Tank et al. 2015: ca 112.5 m.y.; D. W. Taylor & Gee 2014: ca 113 m.y.: fossils), that in Magallón et al. (2013) is around 122.7 m.y., and that in Iles et al. (2014) (107.1-)102.1(-98.8) m.y. ago. However, Löhne et al. (2008: molecules) thought that divergence was only Palaeocene in age, (75-)56.4(-38) m.y.a., while Bell et al. (2010) offered a still younger date of (56-)42, 38(-25) m.y.; Yoo et al. (2005) pegged the crown group age to 44.6 ± 7.9 m.y., while in Naumann et al. (2013), at around 94.75 m.y., the age was intermediate. Whether or not an [Amborellales + Hymphaeales] clade is recognized seems to be irrelevant.

Early fossil-based estimates for the age of this group were only ca 90 m.y. (Crepet et al. 2004), but substantially earlier dates are likely (Friis et al. 2009b). There are fossils of stem-group Nymphaeaceae, Cabombaceae and/or [Nymphaeaceae + Cabombaceae] from several parts of the world in the Lower Cretaceous (e.g. D. W. Taylor et al. 2001, 2008; Friis et al. 2011). Although other fossils possibly of this group (to a certain extent characters of the two families are combined) are known from the Barremian-Aptian deposits 125-113 m.y.o. in Portugal (Friis et al. 2001), they may also be from a member of Austrobaileyales (Gandolfo et al. 2004). See also von Balthazar et al. (2008) for another fossil perhaps assignable to this general [Nymphaeales-Austrobaileyales] area. Indeed, a dozen or more genera based on fossil seeds have been described that belong in this general area, and exotestal seeds e.g. with tall exotestal cells with sinuous antinclinal walls were diverse in the Middle Albian-Middle Aptian some 115-105 m.y.a., and their limitedoccurrence seems to reflect extensive extinction at around this time (Friis et al. 2017b, 2018b, c and references). D. W. Taylor et al. (2008, see also Taylor 2008) noted how inclusion of different fossils in phylogenetic analyses affected trees around here and so our ideas of relationships.

Pluricarpellatia, probably to be placed in or near Cabombaceae (Doyle & Endress 2014), is known from the Early Cretaceous (Mohr et al. 2008). The Early Cretaceous Monetianthus was embedded within crown Nymphaeaceae in morphological analyses (Friis et al. 2009b, but c.f. 2011; see also Doyle & Upchurch 2014; Doyle 2016), and this may be true for the mid-Albian Carpestella, from Virginia (Doyle & Endress 2014); both these genera have very small flowers. The distinctive reticulate-perforate pollen of Monetianthus would then be independently derived within Nymphaeales, but other analyses also placed the genus at the node above Nymphaeales along the spine of the angiosperm tree (Friis et al. 2009b). Yoo et al. (2005) thought that the ca 90 m.y.o. fossil Microvictoria was stem group Nymphaeales, although other studies suggested it was crown-group Nymphaeaceae (Gandolfo et al. 2004; Endress 2006; Friis et al. 2011), and on it goes.

Evolution:Divergence & Distribution. D. W. Taylor et al. (2008, see also Taylor 2008) discuss the vegetative evolution of the group (see some of the characters above); the inclusion of different fossils affected relationships, and hence evolutionary interpretations, in analyses of morphological variation. Friis et al. (2011: fig. 20.2) discussed diversification in this clade in some detail, assigning many Palaeogene fossils to the two families.

Ecology & Physiology. Members of this clade, along with other angiosperms, may have come to dominate aquatic habitats in Europe by the Albian ca 105 m.y.a. (Sender et al. 2010).

Pollination Biology & Seed Dispersal. Generalist pollination is common here (Gotttsberger 2016); see also Luo et al. (2018) for a summary and references.

Genes & Genomes. For the chloroplast inverted repeat, see Graham and Olmstead (2000).

Chemistry, Morphology, etc. For micromorphological details of vessels and tracheids, see Carlquist and Schneider (2009) and Schneider et al. (2009); details of the wall structure of tracheids, at least, are very distinctive. Note that Carpenter (2005) described stomata as being largely variants of the actino/stephanocytic types; only one member of Cabombaceae was studied. D. W. Taylor (2008) outlined the vegetative morphology of this clade.

The flowers are often not strictly axillary. Warner et al. (2008, 2009) discuss perianth evolution, and in Warner et al. (2008) there is a useful summary on the literature on perianth morphology. Zini et al. (2016) described the distinctive nucellar epidermis of the ovules as being an epistase.

Cabombaceae are rather small-flowered waterlilies with
few ovules or seeds in each carpel; they have floating stems and all the flower parts are free.

Evolution:Pollination Biology & Seed Dispersal.Brasenia is wind pollinated, while Cabomba has paired nectaries on its inner tepals and is pollinated by flies. M. L. Taylor and Williams (2009) describe details of reproduction of Cabomba from pollination to fertilization, while Schneider and Jeter (1982) discuss its pollination. For more details, see Erbar (2014) and Gottsberger (2016)

Chemistry, Morphology, etc. The root endodermis has a Casparian strip and suberin lamellae. It is unclear how to interpret nodal anatomy. In Cambomba a trace leaves from each member of a vascular bundle pair which shortly thereafter fuse commissurally, creating a nodal plexus; the foliar traces fuse and then divide, providing two petiolar bundles (Moseley et al. 1984). The peltate leaves are spirally arranged, although in some taxa they are uncommon. The more or less dichotomously-divided submerged leaves are opposite; for leaf morphology, see Rutishauser and Sattler (1987).

There are five vascular bundles in the sepals and three vascular bundles in the petals of Cambomba, in both cases there is a single trace leaving the floral axis (Moseley et al. 1984). Stamens are sometimes physically close to each nectary and then they appear paired (Ørgaard et al. 1992). Pollen of Cabomba has striate exine. Although the endexine of mature pollen of Brasenia schreberi is not lamellate, it is laid down in plates (M. L. Taylor & Osborn 2006).

The granular infratectum of the pollen of Podostemaceae has been compared with that of Cabombaceae; both are aquatics (Passarelli et al. 2002).

Age. E. L. Schneider et al. (2004) suggested an age for the family of ca 121 m.y.a., Magallón et al. (2013) an age of around 100.1 m.y., while Iles et al. (2014) suggested an age of (99.6-)95.5(-92.9) m.y. ago. However, estimates in Bell et al. (2010) are only (49-)32, 29(-15) m.y. and those in Zhou et al. (2014) (60.6-)28.2(-3.8) m.y., while those in Naumann et al. (2013) are around 51.8 or 40.8 m.y., somewhat intermediate.

The Late Aptian/Early Albian Cretaceous Monetianthus, from Portugal, is embedded in Nymphaeaceae in morphological analyses (Friis et al. 2009b). Microvictoria, a somewhat later fossil from the Turonian ca 90 m.y. old and found in New Jersey, U.S.A., is very like Victoria (= Nymphaea). Victoria has "paracarpels" immediately surrounding the gynoecium, and these are also found in Microvictoria; indeed, flowers of this latter are like those of Victoria in almost all respects, although they are less than 1/10th their size (Gandolfo et al. 2004). Jaguariba is assignable to crown group Nymphaeaceae; it is from the Aptian Crato flora of northeast Brazil and is some 115 m.y.o. (Coiffard et al. 2013a). For Cecilanthus, from early Cenomanian Maryland ca 100 m.y.a., see Herendeen et al. (2016) and above).

Age. Friis et al. (2017b) were inclined to group Notonuphar, fossil seeds from Eocene Seymour Island, Antarctica, with Nuphar, although it has tall, thick-walled testal cells like those of Brasenia (Cabombaceae).

Nymphaeaceae are the quintessential waterlilies, with
large flowers, usually many free perianth parts and stamens, and many ovules in
each carpel, the placentation usually being clearly laminar. Many species have no stem, the plants essentially being aquatic rosette plants.

Evolution:Divergence & Distribution. The family is thought to have been much more diverse in earlier epochs, distinctive seeds with a micropylar and palisade exotesta with sinuous anticlinal walls that can be assigned here being common in the Cretaceous (Friis et al. 2009b, 2011, 2017b; see also above). Recently, fossils assigned to crown group Nymphaeaceae (as Jaguariba) have been found in the Aptian Crato flora, some 115 m.y.o. in northeast Brazil (Coiffard et al. 2013a) and the first seeds from the Southern Hemisphere have been described in Eocene deposits from Seymour Island, Antarctica (Friis et al. 2017b).

Indeed, although the family is widespread and probably very old, individual clades within it are relatively localized, and it has even been suggested that crown group diversification may have occurred in the northern hemisphere in the early Caenozoic (Löhne et al. 2008; see also Friis et al. 2011).

Ecology & Physiology.Barclaya rotundifolia is a terrestrial plant of wet forests in western Malesia.

Pollination Biology & Seed Dispersal. Thermogenesis has been detected in the flowers of some Nymphaeaceae (Seymour 2001; Seymour & Matthews 2006). Beetles and a variety of other insects, including flies, are pollinators (e.g. Gandolfo et al. 2004; Padgett 2007; Thien et al. 2009). Scarab beetles (Cyclocephalini) may have pollinated night-flowering water lilies for some 100 m.y.; they pollinate species both in America, where the beetles are common, and in Africa, where the beetles are otherwise very uncommon (Ervik & Knudsen 2003; Moore & Jameson 2013). Beetle pollination may have occurred even in the early small-flowered members of the fammily (M. L. Taylor et al. 2013 and references). The distinctive flowers of Ondinea (= Nymphaea ondinea), wind pollinated, are derived from Nymphaea-type flowers (Löhne et al. 2009). Schneider (1979) summarized information about the pollination biology of the family; see also Erbar (2014), Gottsberger (2016: Table 2, much detail), Luo et al. (2018) and Coiro and Barone Lumaga (2018: floral epidermal micromorphology).

The progamic phase, the time between pollination and fertilization, is notably short, up to a mere 8 hours, as in at least some other aquatic angiosperms (including Nelumbo: see Williams et al. 2010).

Dehiscence of the fruit of Nymphaeoideae is by swelling of the mucilage inside it, whereupon the wall splits irregularly.

Plant-Animal Interactions. Nymphaeaceae are host plants of reed beetles, Chrysomelidae-Donaciinae (see also Poales: Kölsch & Pedersen 2008: much discussion on the age and evolution of the group). Interestingly, Enterobacteriaceae near Buchnera are believed to produce the material that makes up the cocoon that characterises Donaciinae, a group that is also noted for the ability of the larvae to grow under water (Kölsch & Pedersen 2010).

Genes & Genomes. A genome duplication in Nuphar is estimated to have occurred (76.8-)72.8(-67.9) m.y.a. (Vanneste et al. 2014b); it is pegged at the level of [Nymphaea + Nuphar] and dated to around 106.3 m.y.a. (Landis et al. 2018: App. S1), so its extent depends on confirmation of the position of Nuphar...

Chemistry, Morphology, etc. The root endodermis has a Casparian strip. There are sometimes sclerenchymatous diaphragms in the pith. The vasculature of the stem is exceedingly complex, especially at the node, with peduncular complexes forming internally, however, basic stem structure is unlike that of monocotyledons; the primary xylem is mesarch (Weidlich 1980 and references). Schneider et al. (2008, 2009) and Schneider and Carlquist (2009) discuss stem tracheids and root vessels, emphasizing the rather arbitrary distinction between vessels and tracheids; Carlquist (2012c) suggested that there were no vessels. The astrosclereids of Nuphar and Nymphaea, at least, have calcium oxalate crystals in the walls (Fink 1991). Stipules may be adaxial and bicarinate or paired and lateral.

In both Nuphar and Nymphaea flowers and even branches may replace leaves in the genetic spiral (e.g. Cutter 1957a, b; Groß et al. 2006). Cutter (1957b) noted that the leaf apparently subtending the flower of Nuphar was in fact born on the flower stalk; if a prophyll, it should be noted that it is abaxial in position. For discussion as to whether or not Nuphar has bracts, see Schneider et al. (2003).

Flower parts are generally whorled (see Endress & Doyle 2015 and references). Yoo et al. (2010) discuss the evolutionary/developmental relationship between sepals and petals; see also Doyle and Endress (2011), who suggest that Nuphar has both tepals and petals (the latter the smaller, inner, petal-like structures). Schneider (1976) and Moseley and Uhl (1985) note that the vascular supply to perianth and androecial members consists of two radially associated bundles. In Euryale the filaments are quite slender and are basally adnate to the staminodes; it is unclear if it has free nuclear endosperm (Floyd & Friedman 2001 - see also Kanna 1964, 1967 for endosperm development in the family). Weberling (1989) suggested that in at least some Nymphaeaceae the individual carpels were free laterally, if adnate to the central axis inside and to "hypanthial" tissue outside (see also von Balthazar et al. 2008). The ovules of Victoria and Euryale are massive affairs (Zini et al. 2016). Zhou and Fu (2008) found that at anthesis, but not before or after, the micropyle of Nuphar was bistomal, not endostomal. Weberling (1989) also described how in Nuphar axial tissue separates from the gynoecium when the fruits are ripe, so exposing the basically free carpels; if this is correct (but it seems rather unlikely, see Moseley 1965 for a description of what goes on), its gynoecium would be very similar to that of other Nymphaeaceae; Padgett (2007) described dehiscence as being along lines in the septal and ovarian walls where aerenchymatous tissue had developed. For embryo development and germination in Nymphaea, see Baskin and Baskin (2007b), the embryo may be fully developed before germination begins. The seedling axis in some species of Nymphaea has a lateral projection.

Phylogeny.Nymphaea s. str. was monophyletic in a phylogenetic analysis of vegetative characters, but without much support (D. W. Taylor 2008). For a phylogeny of Nymphaea, see Borsch et al. (2007, 2012); the genus definitely includes the wind-pollinated and usually apetalous Ondinea, but some relationships lacked much support, e.g. the position of [Euryale + Victoria] as sister to Nymphaea s.l. (see also Gruenstaeudl et al. 2017: support also not that strong). However, in some studies the spiny Victoria and Euryale are embedded in Nymphaea s.l. (Löhne et al. 2007, 2009; Borsch et al. 2008; c.f. Friis et al. 2011); see also D. W. Taylor and Gee (2014) and Coiro and Barone Lumaga (2018) for relationships, the former integrating data from fossils and the latter floral epidermal micromorphology in their analyses.

Classification. The inclusion of Nuphar in Nymphaeaceae needs to be confirmed (see above). A broad circumscription for Nymphaea seems best for the time being.